There is a need in many applications for measuring a set of pressures or multiple pressures along a given surface. These measurements, for example, are made in a wind tunnel where sensors may be placed on the wing of an airplane at different locations. The wind tunnel subjects the model, such as the wing of an airplane or other model, to extreme temperatures, vibrations and high wind velocity. A common method, which is employed, is to use a pressure scanner. Such a scanner essentially is a small box with a number of pressure sensors inside. Tubes are run from the pressure surface to the scanner in order to measure the pressure. As one can ascertain, such a device is depicted in U.S. Pat. No. 3,930,412 issued on Jan. 6, 1976 to A. D. Kurtz, et al. and entitled “ELECTRICALLY SCANNED PRESSURE TRANSDUCER CONFIGURATIONS.” That patent which is assigned to Kulite Semiconductor Products, Inc., the assignee herein. There is shown a plurality of individual pressure transducers which are mounted or fabricated within a common housing. Each pressure transducer is associated with a separate and distinct pressure port and can be subjected to a different one of a plurality of pressure sensitive locations to be monitored. The pressure transducers are electrically scanned by means of a scanning device such as a shift register or counter so that their individual outputs can be recorded. If one makes reference to the above-noted patent, one will see that the discussion of wind tunnel measurements is given and various other publications which are pertinent to such a scanner are also depicted.
While the scanner has been utilized, the disadvantages are that the response rate of such a system is greatly lowered because of the fact that long tubes must be run from the scanner module to various points along the wing of an aircraft. As one can ascertain, the wing of an aircraft could be extremely long and therefore the pressure tubes that are directed from the pressure scanner are long and therefore is very difficult to get frequency data more than a few tens of hertz. In any event, as depicted from the above-noted patent, it has the advantage of being a compact system and does not require a great deal of cabling from the scanner to the outside computer system.
Another method of measuring the pressure along a surface is to place individual pressure sensors at each measurement point. The output of each of these sensors is then directed back to a central data acquisition system. This configuration has the advantage of allowing high frequency data to be taken but it makes the measurement much more complicated because the output from each pressure sensor must be digitally converted and electrical lines must be run from the sensor to a central data acquisition system. This also requires a great deal of time installing the system as well as retrieving the data from the system. In any event, based on the above, it is a object of the present invention to provide a pressure system for measuring a multiplicity of pressures as in a wind tunnel, each under extreme conditions of temperature and vibration and to enable the system to be simply implemented and maintained.